HALIFAX—A geologist using aerial photos appears to have solved a mystery over the origin of the headstones for victims of the Titanic buried in a Halifax cemetery.

There are 150 Titanic headstones in the Fairview Lawn Cemetery and all but one is made out of the same stone.

Halifax geologist Barrie Clarke says he knew the stones purchased by the White Star Line in the fall of 1912 were made out of gabbro or black granite, but it wasn’t clear which quarry the stone came from because there was no archival record.

He began looking into the issue when a headstone was damaged and needed to be repaired, finding that the stone was 421 million years old, which narrowed down the quarries to ones in New Brunswick and Maine.

Using old aerial photos from the New Brunswick archives, Clarke told Global News that he found 16 black granite quarries in the area of St. George and matched the stone to Bocabec, N.B.